Centering attachment for lathes.



Patented Aug. 26, I902.

J. M. FLEMING.

CENTERING ATTACHMENT FOR LATHES.

(Application filed Oct. 17, 1901.)

(No Model.)

cm c0. PHOTO-LITHO wnumcrmn o c UNTTnn STATns PATENT. OFFICE.

JOHN MILLER FLEMING, OF OTTAIVA, CANADA, ASSIGNOR OF ONE-HALF TO\VILLIAM BOTHIVELL, OF OTTAlVA, CANADA.

CENTERING ATTACHMENT FOR LATHES.

SPECIFICATION forming part of Letters Patent No. 707,573, dated August26, 1902.

Application filed October 1'7, 1901. Serial No. 78,989. (No model.)

To (tZZ whom it may concern:

Beit known that 1, JOHN MILLER FLEMING, machinist, of the city ofOttawa, in the county of Carleton, in the Province of Ontario and 5Dominion of Canada, haveinvented a new and useful Centering Attachmentfor Lathes, of which the following is a specification.

My invention relates to improvements in centering attachments forlathes; and the object of my invention is to devise an attachment forlathes by means of which a hole may be bored in the exact center of theend of a piece of work to be turned on a lathe for the center point ofthe lathe, further objects being to make such a device simple and cheapin construction and positive in its action; and it consists,essentially, of a cup-shaped portion with means forsecuring the same tothe tailpiece of the lathe while permitting of its rotation, a centraldrill being provided having means for adjusting it in a forward orbackward direction and means for pre venting its rotation, the variousparts being constructed and arranged in detail as hereinafter moreparticularly described.

Figure l is a perspective view of my attachment. Fig. 2 is a sectionalView of the same. Fig. 3 is a detail of an alternative form of drillwhich may be used in connection with 0 my device.

In the drawings like letters of reference indicate corresponding partsin each figure.

A is the rotatable portion comprising the cup-shaped portion a and acylindrical portion a, in which is a central hole c 13 is the body ofthe device, which is substantially cylindrical in form and is providedwith an outwardly-extending reducedcylindrical portion 1), designed tofit in the hole a 0 At its opposite end the body of the device is formedwith an inwardly-extending central circular hole or depression Z).

O is a supporting-piece having a tapered portion 0 to fit in and securethe device to the tailpiece of'the lathe and also having a cylindricalportion 0, designed to fit in the hole or depression I) in the body ofthe device.

A central longitudinal holeD is formed continuously in thesupporting-piece O, the body B, and the rotatable portion A. A suitabledrill E is provided and inserted in this longitudinal hole and held fromturning therein preferably-by means of a stop F, of any suitable form,which is inserted in a slot 6, formed in the drill.

Any suitable means may be provided for advancing or withdrawing thedrill E; but the means which I prefer to employ is as follows: Teeth eare formed on the drill E. A

pinion Gis provided having teeth g, designed 6o to engage the teeth 6 ofthe drill E. This pinion is secured on a suitable shaft g, which isjournaled in lugs b 19 formed on and extending outwardly from-the bodyportion 1-3.

A lever, crank, or handle of any suitable form is provided for rotatingthe pinion G.

I prefer, however, to employ for this purpose a lever II, which isfirmly secured to the shaft g. I

In order to prevent the conical cup from slipping off theencl of thecylindrical reduced portion b of the body B and in order to permit ofits free rotation thereon, a slot orgroove b is formed in thecircumference of the cylindrical portion 1), and a screw I is providedand is screwed through the cylindrical portion C6 in such a position asto just enter the groove 17*. The supporting-piece O is held securely inthe body B by means of a suitable set-screw J. It will thus be seen thatthe ta- 8o pered portion O of the device may be jammed into thetailpiece of the lathe, and this will hold the body portion of theattachment rigidly with its axis coinciding with the axis of the-lathe,so that if a piece of shafting or other round or symmetrical materialbeattached to the head-stock in theordinary way and its opposite end beinserted in the cup a as soon as the lathe is started the work willturn, and owing to the friction between the end of 0 the piece of workand the cup at the rotatable portion will be caused to rotate. The drillE, which does not rotate, may now be advanced and will drill a hole intothe end of the work, and owing to the conical shape of the cup this holewill of necessity be in the exact center of the end of the piece ofwork. A thrustbearing is provided between the end of the cyndrical parta of the rotatable portion A and the shoulder b of the body portion B.This hearing may consist simply of a ring of brass or other material;but for small work I prefer to provide ball-bearings at this point,which are constructed, preferably, as follows: Circular rings K and Kare'provided having holes and 7c, in which are inserted steel balls 70the diameter of which is slightly greater than the combined thicknessesof the two rings K and K.

In order to give the work the best possible grip in the cup, a pluralityof slots a may be formed therein, the edges of which will cause agreater friction between the work and the cup.

A separate tip or bit for the drill may be provided and secured to thetoothed portion or stock by any suitable means. I have shown one methodof securing such a tip to the stock in Fig. 3, in which E is the tootheddrillstock, and E is the bit. The stock E is provided with a hole orrecess c and the bit has a corresponding extension 6 A hole 0 is boredthrough the stock at the edge of the hole a and through the edge of theextension 6 and a locking-pin e is inserted therein to hold the bit inplace. When a point breaks, all that is necessary is to remove the bitand regrind it or to replace the bit with a new one, and the toothedportion or stock will last indefinitely.

In centering a piece of work with my device all that is necessaryis tosecure one end of the work to the head of the lathe and insert the otherend in a cup to. The work is then rotated, the drill is advanced, andthe hole is drilled and countersunk in the exact center of the work, andit will thus be seen that the time which ittakes to drill a hole will begreatly reduced by the use of my devlce.

It will of course be understood that although the cup-shaped portion ofmy device is shown and described as conical it may be made flaring or ofother curved form without departing from the spirit of my invention;also, I might provide cups of a variety of cross-sections for other thancircular stock, the essential feature of the cup being that its internaldiameter must be largest atits mouth and gradually get shorter towardthe inner portion of the cup. It will also be understood that certainother mechanical equiva lents might be substituted for the various partsof the device without departing from the spirit of my invention, such asa wormand-rack gear in place of the pinion-and-rack gear for advancingand withdrawing the drill;

also, the body and the supporting part of the device might be made inone piece; but the construction and form shown is that which I considerpreferable in practice.

I am aware that it is not new to use a conical or funnel-shaped cup forthe purpose of centering work to be turned on a lathe; but in my devicethe said cup is rotatably secured to the body portion in such a mannerthat it may be readily removed and a larger cup substituted therefor, ifit be desirable, and this point of advantage has not been attained inany other centering device. It may further be pointed out that the meanswhich I have devised for securing the cup rotatably to the body of thedevice is extremely cheap in construction, as only one extra partnamely,the screw I-is necessary, and in previous constructions at least threeadditional parts were required;

What I claim as my invention is- 1.- In combination, a body portionhaving a cylindrical extension at the front end, a cup-shaped portionhaving its rear end rotatably mounted on said cylindrical extension, asupporting-piece at the rear of said body portion, said cup-shapedportion, body portion and supporting-piece having an axial passage, adrill longitudinally movable in said passage, means for holding the sameagainst rotary movement relative to the body, and means for advancingand retracting the drill substantially as described.

2. In combination, the body portion having a cylindrical extension atthe front end with a circumferential groove formed thereon, a cup-shapedportion having its rear end rotatably mounted on said cylindricalextension, a key extending through the rear end of said cup-shapedportion and into said groove, a supporting-piece at the rear end of saidbody portion, said cup-shaped portion, body portion and supporting-piecehaving an axial passage, a drill longitudinally movable in said passage,means for holding the same against rotary movement relative to the body,and means for advancing and retracting the drill, substantially asdescribed.

Signed atthe city of Ottawa this 9th day of October, 1901.

JOHN MILLER FLEMING.

Witnesses:

E. P. FETHERSTONHAUGH, F. W. SMITH.

